1. Field of the Disclosure
The present disclosure relates generally to inkjet printheads, and more particularly, to inkjet printheads that provide long print swaths on a print medium.
2. Description of the Related Art
A typical inkjet printer includes an inkjet printhead that is allowed to pass multiple times across a width of a print medium (such as a paper/document to be printed) during a printing operation. The inkjet printhead may have thermal, piezoelectric or mechanical actuating fluid ejectors (fluid ejecting chips). On completion of the printing operation, a print on the print medium is defined as an established number of print swaths. As used herein the term, ‘print swath’ may relate to a stripe of print across the print medium that the inkjet printhead may create at a time. It has been observed that printing speed for a print medium is majorly affected by the length of a print swath (longer the print swath, higher the speed for printing the print medium). Various approaches have been devised to achieve a longer print swath. For example, lengths of fluid ejecting chips of an inkjet printhead may be increased for achieving a longer print swath. Further, arraying of multiple fluid ejecting chips in a line within an inkjet printhead may also assist in achieving a longer print swath.
Also, fluid ejecting chips of an inkjet printhead are generally fabricated in order to have rectangular shapes. A rectangular shape of a fluid ejecting chip assists in maximizing the available print swath while leading to a practical placement of electrical interconnects at respective long end portions of the fluid ejecting chip, i.e., along respective breadths of the fluid ejecting chip. Further, in a typical fluid ejecting chip, a top side encapsulant is used for protecting electrical interconnect bond pads and bond wires from a corrosive fluid (such as ink) environment that any inkjet printhead may experience during storage, service and maintenance thereof. The top side encapsulant is fabricated during circuit assembly of the inkjet printhead in a two-step process. Specifically, uncured liquid encapsulant is initially disposed over the bond pads and the bond wires with the help of an automated dispenser. Subsequently, a thermal cure process is used for curing/solidifying the dispensed liquid encapsulant.
FIG. 1 depicts a typical tri-color fluid ejecting chip 100 that is rectangular in shape and includes slotted fluid vias 102, 104 and 106. The fluid vias 102, 104 and 106 may be for colored fluids such as cyan, magenta and yellow, respectively. It should be understood that the fluid ejecting chip 100 may include any number of fluid vias for any colored fluid as desired. The fluid ejecting chip 100 includes a plurality of bond pads 112 configured at long end portions 122 and 124 of the fluid ejecting chip 100, i.e., along respective breadths of the fluid ejecting chip 100. Further, the fluid ejecting chip 100 includes a plurality of bond wires 132 that form electrical interconnects at the long end portions 122 and 124 of the fluid ejecting chip 100. The bond wires 132 connect power or control signals to the bond pads 112 that connect to respective fluid ejecting elements (not shown) configured adjacent to the fluid vias 102, 104 and 106 of the fluid ejecting chip 100. A protective encapsulant 142 seals any exposed fluid ejecting chip wiring, the bond wires 132 and power/control signal connection wiring from a fluid. Overcoat layers (not shown) protect the fluid ejecting chip and power/control signal wiring not covered by the encapsulant 142. As depicted in FIG. 1, ‘D1’ represents width of the top-side encapsulant, ‘D2’ represents length of the top-side encapsulant, and ‘D3’ represents length of a print swath that may be obtained by employing the fluid ejecting chip 100.
It has been observed that an encapsulant's profile and footprint have tolerances arising from many variable factors, such as a viscosity of the encapsulant, an alignment of the automated dispenser with respect to a fluid ejecting chip, such as the fluid ejecting chip 100, a location of the dispensed encapsulant, and expansion of the encapsulant during the thermal cure process. Further, arrangement of a plurality of fluid ejecting chips, such as the fluid ejecting chip 100, in an array of adjacent rows may result in significant footprint tolerance of the encapsulant, thereby challenging close tiling of the fluid ejecting chips required to achieve long print swaths and to minimize paper skew effects. Furthermore, it has been observed that location/position of bond pads is vital to the arrangement of the fluid ejecting chips, as the bond pads need to be configured appropriately in order to facilitate an easy fan-out of bond wires from the fluid ejecting chips to a circuit assembly substrate of an inkjet printhead. The term ‘circuit assembly’ as used herein above relates to the connection between a fluid ejecting chip, such as the fluid ejecting chip 100, and a printhead controller. Accordingly, the separation between the adjacent rows of the fluid ejecting chips, during fabrication, tends to increase, thereby making it difficult to tile the fluid ejecting chips closely and increasing the chances for paper skew print defects. The aforementioned aspect with regard to encapsulant tolerance and tiling of fluid ejecting chips is explained in conjunction with FIG. 2.
FIG. 2 is a schematic depiction of a wide swath inkjet printhead 200 that includes conventional fluid ejecting chips 220, 240 and 260. Each fluid ejecting chip of the fluid ejecting chips 220, 240 and 260 of the wide swath inkjet printhead 200 includes fluid vias configured therewithin and bond pads configured on respective long end portions. Specifically, the fluid ejecting chip 220 includes fluid vias 222, 224 and 226 for cyan, magenta and yellow colored-fluids (inks), respectively. Further, the fluid ejecting chip 220 includes a plurality of bond pads 228 configured at long end portions 230 and 232 thereof. Similarly, the fluid ejecting chip 240 includes fluid vias 242, 244 and 246 for cyan, magenta and yellow colored-fluids (inks), respectively. Further, the fluid ejecting chip 240 includes a plurality of bond pads 248 configured at long end portions 250 and 252 thereof. Further, the fluid ejecting chip 260 includes fluid vias 262, 264 and 266 for cyan, magenta and yellow colored-fluids (inks), respectively. Further, the fluid ejecting chip 260 includes a plurality of bond pads 268 configured at long end portions 270 and 272 thereof. For such an inkjet printhead 200, distance between fluid vias for the same colored-fluid (ink), such as the fluid vias 222 and 242, of consecutive fluid ejecting chips, such as the fluid ejecting chips 220 and 240, needs to be minimized in order to reduce the paper skew print defects. For example, distance ‘D4’ between the fluid vias 222 and 242 needs to be minimized in order to reduce the effects of paper skew on print quality. Further, ‘D5’ represents the length of encapsulant tolerance set for the inkjet printhead 200. FIG. 2 also depicts the direction of paper travel (depicted by arrow ‘A’) with respect to the alignment of the fluid ejecting chips 220, 240 and 260.
FIG. 3 depicts dot patterns to illustrate effects of paper skew on print quality. Specifically, FIG. 3 depicts a first dot pattern (depicted as ‘Dot pattern 1’) without any printhead skew, drop skew error and drop alignment error for a near row of a plurality of nozzles 310 and a far row of a plurality of nozzles 320. Further, FIG. 3 depicts a second dot pattern (depicted as ‘Dot pattern 2’) for a linear travel skew, i.e., the second dot pattern is associated with printhead skew, drop skew error and drop alignment error for the nozzles 310 and the nozzles 320. It may be observed that distance between the nozzles 310 and the nozzles 320, in the direction of paper travel (depicted by arrows ‘B’ and ‘C’) affects location of fluid drops on a paper (or any other print medium) in the presence of printhead skew, drop skew error and drop alignment error. The second dot pattern depicts that the printhead skew results in drop skew error where dots are skewed on the paper. In addition, dots from the near row of the nozzles 310 may incorrectly align with dots from the far row of the nozzles 320, thereby resulting in drop alignment error, as depicted in the second dot pattern.
FIG. 4 depicts a third dot pattern (depicted as ‘Dot pattern 3’) and a fourth dot pattern (depicted as ‘Dot pattern 4’) to illustrate the relation between nozzle distance and skew effects on drop location and print quality. Specifically, the third and the fourth dot patterns depict that nozzles, such as a plurality of nozzles 410 and plurality of nozzles 420, which are narrowly separated and have a large skew angle, eject drops that are disposed in a manner (in terms of respective locations) similar to that for nozzles, such as a plurality of nozzles 430 and a plurality of nozzles 440, which are widely separated and have a small skew angle. It may also be observed that greater nozzle-to-nozzle 115 distance between adjacent rows of an inkjet printhead intensifies the skew effects on drop location and print quality. Accordingly, the nozzle-to-nozzle distances between the adjacent rows need to be minimized in order to minimize effects of the skew angle on drop location and print quality. In FIG. 4, directions of paper travel are depicted by arrows ‘D’ and ‘E’.
An alternate design of fluid ejecting chips in an inkjet printhead may be used for addressing the aforementioned problems associated with skew effects and close tiling of the fluid ejecting chips. FIG. 5 is a schematic depiction of an alternate design for an inkjet printhead. The inkjet printhead 500 includes a plurality of fluid ejecting chips arranged in a plurality of rows, such as a first row 502 and a second row 504. Each fluid ejecting chip of the plurality of fluid ejecting chips includes a first set of fluid ejecting chips, such as fluid ejecting chips 510 and 530, arranged in the first row 502 of the plurality of rows. Each fluid ejecting chip of the first set of fluid ejecting chips includes a first edge and a second edge opposite to the first edge. Specifically, the fluid ejecting chip 510 includes a first edge 512 and a second edge 514 opposite to the first edge 512. Similarly, the fluid ejecting chip 530 includes a first edge 532 and a second edge 534 opposite to the first edge 532. Further, the first edge and the second edge of the each fluid ejecting chip of the first set of fluid ejecting chips are longitudinal straight edges.
The plurality of fluid ejecting chips also includes a second set of fluid ejecting chips, such as fluid ejecting chips 550 and 570, arranged in the second row 504 of the plurality of rows. As depicted in FIG. 5, the second row 504 is parallel to the first row 502. Each fluid ejecting chip of the second set of fluid ejecting chips includes a first edge and a second edge opposite to the first edge. Specifically, the fluid ejecting chip 550 includes a first edge 552 and a second edge 554 opposite to the first edge 552. Similarly, the fluid ejecting chip 570 includes a first edge 572 and a second edge 574 opposite to the first edge 572. Further, the first edge and the second edge of the each fluid ejecting chip of the second set of fluid ejecting chips are longitudinal straight edges.
The each fluid ejecting chip of the second set of fluid ejecting chips is configured between two consecutive fluid ejecting chips of the first set of fluid ejecting chips in a predetermined orientation such that the second edge of the each fluid ejecting chip of the second set of fluid ejecting chips is in proximity to a respective second edge of a fluid ejecting chip of the two consecutive fluid ejecting chips of the first set of fluid ejecting chips. The predetermined orientation corresponds to an alignment of the each fluid ejecting chip of the second set of fluid ejecting chips at an angle of about 180 degrees)(°) with respect to each fluid ejecting chip of the two consecutive fluid ejecting chips of the first set of fluid ejecting chips. In other words, the each fluid ejecting chip of the second set of fluid ejecting chips is rotated by an angle of about 180° with respect to the each fluid ejecting chip of the first set of fluid ejecting chips. Specifically, the fluid ejecting chip 550 is configured between the fluid ejecting chips 510 and 530 in the predetermined orientation that corresponds to the alignment of the fluid ejecting chip 550 at an angle of about 180° with respect to the fluid ejecting chips 510 and 530. Similarly, the fluid ejecting chip 570 may be configured between the fluid ejecting chip 530 and a consecutive fluid ejecting chip (not shown) of the first set of fluid ejecting chips in the predetermined orientation.
It may be understood that the inkjet printhead 500 is depicted to include only four fluid ejecting chips. However, the inkjet printhead 500 may include any number of fluid ejecting chips required for printing purposes.
Further, the inkjet printhead 500 includes a plurality of fluid vias. The plurality of fluid vias includes a first set of fluid vias configured within the each fluid ejecting chip of the first set of fluid ejecting chips. Specifically, the plurality of fluid vias includes fluid vias 516, 518 and 520 configured within the fluid ejecting chip 510 of the first set of fluid ejecting chips. Similarly, the plurality of fluid vias includes fluid vias 536, 538 and 540 configured within the fluid ejecting chip 530 of the first set of fluid ejecting chips. The plurality of fluid vias also includes a second set of fluid vias configured within the each fluid ejecting chip of the second set of fluid ejecting chips. Specifically, the plurality of fluid vias includes fluid vias 556, 558 and 560 configured within the fluid ejecting chip 550 of the second set of fluid ejecting chips. Similarly, the plurality of fluid vias includes fluid vias 576, 578 and 580 configured within the fluid ejecting chip 570 of the second set of fluid ejecting chips. As depicted in FIG. 5, fluid vias of the first set of fluid vias and the second set of fluid vias have the same lengths.
Further, a fluid via of the first set of fluid vias configured in proximity to the first edge of the each fluid ejecting chip of the first set of fluid ejecting chips and a fluid via of the second set of fluid vias configured in proximity to the second edge of the each fluid ejecting chip of the second set of fluid ejecting chips, are adapted to carry a fluid of a first type, such as cyan color. Specifically, the fluid via 516 configured in proximity to the first edge 512 of the fluid ejecting chip 510 and the fluid via 560 configured in proximity to the second edge 554 of the fluid ejecting chip 550 are adapted to carry the fluid of the first type. Similarly, the fluid via 536 configured in proximity to the first edge 532 of the fluid ejecting chip 530 and the fluid via 580 configured in proximity to the second edge 574 of the fluid ejecting chip 570 are adapted to carry the fluid of the first type.
Furthermore, a fluid via of the first set of fluid vias configured in proximity to the second edge of the each fluid ejecting chip of the first set of fluid ejecting chips and a fluid via of the second set of fluid vias configured in proximity to the first edge of the each fluid ejecting chip of the second set of fluid ejecting chips, are adapted to carry a fluid of a second type, such as yellow color. Specifically, the fluid via 520 configured in proximity to the second edge 514 of the fluid ejecting chip 510 and the fluid via 556 configured in proximity to the first edge 552 of the fluid ejecting chip 550 are adapted to carry the fluid of the second type. Similarly, the fluid via 540 configured in proximity to the second edge 534 of the fluid ejecting chip 530 and the fluid via 576 configured in proximity to the first edge 572 of the fluid ejecting chip 570 are adapted to carry the fluid of the second type.
Moreover, the fluid via 518 of the fluid ejecting chip 510 and the fluid via 558 of the fluid ejecting chip 550 are adapted to carry a fluid of a third type, such as magenta color. Similarly, the fluid via 538 of the fluid ejecting chip 530 and the fluid via 578 of the fluid ejecting chip 570 are adapted to carry the fluid of the third type.
In addition, the inkjet printhead includes a plurality of bond pads. The plurality of bond pads includes a first set of bond pads configured along the first edge of the each fluid ejecting chip of the first set of fluid ejecting chips for distributing power or control signals to fluid ejectors within the each fluid ejecting chip of the first set of fluid ejecting chips. Specifically, the plurality of bond pads includes bond pads 522 configured along the first edge 512 of the fluid ejecting chip 510 for distributing power or control signals to fluid ejectors (not shown) within the fluid ejecting chip 510. Similarly, the plurality of bond pads includes bond pads 542 configured along the first edge 532 of the fluid ejecting chip 530 for distributing power or control signals to fluid ejectors (not shown) within the fluid ejecting chip 530. Further, the first set of bond pads are capable of distributing power or control signals to the fluid ejectors within the each fluid ejecting chip of the first set of fluid ejecting chips through a first set of wires (not shown).
The plurality of bond pads further includes a second set of bond pads configured along the first edge of the each fluid ejecting chip of the second set of fluid ejecting chips for distributing power or control signals to fluid ejectors within the each fluid ejecting chip of the second set of fluid ejecting chips. Specifically, the plurality of bond pads includes bond pads 562 configured along the first edge 552 of the fluid ejecting chip 550 for distributing power or control signals to fluid ejectors (not shown) within the fluid ejecting chip 550. Similarly, the plurality of bond pads includes bond pads 582 configured along the first edge 572 of the fluid ejecting chip 570 for distributing power or control signals to fluid ejectors (not shown) within the fluid ejecting chip 570. Further, the second set of bond pads are capable of distributing power or control signals to the fluid ejectors within the each fluid ejecting chip of the second set of fluid ejecting chips through a second set of wires, such as a plurality of wires 564, as shown in FIG. 6. The inkjet printhead 500 also includes an encapsulant fabricated over the first set of bond pads and the second set of bond pads, in the form of a layer 506, as depicted in FIGS. 5 and 6.
The aforementioned arrangement of the fluid ejecting chips 510, 530, 550 and 570 and the plurality of bond pads, as depicted in FIG. 5, assists in counteracting the fluid ejecting chip tiling problem. Specifically, the plurality of bond pads, such as the bond pads 522, 542, 562, and 582, are placed on the respective first edges 512, 532, 552 and 572 of the fluid ejecting chips 510, 530, 550 and 570 that are positioned in alternate orientations (i.e., rotated by an angle of about 180° with respect to each other) to form an array along a direction of a print media's length (such as length of a paper). Further, distance between a fluid via (such as the fluid via 516) of a fluid ejecting chip of the first row 502 (such as the fluid ejecting chip 510) and a fluid via (such as the fluid via 560) of a consecutive fluid ejecting chip of the second row 504 (such as the fluid ejecting chip 550) that carry the fluid of the same type/color, is minimized by way of such an arrangement. Further, such a distance (as depicted by a distance ‘D6’) is independent of encapsulant footprint tolerance.
By way of such an aforementioned arrangement of the inkjet printhead 500, power/control signals distribution may be routed within the plurality of fluid ejecting chips of the inkjet by modifying dimension/size of each fluid ejecting chip of the inkjet printhead 500. For example, FIG. 6 depicts the fluid ejecting chip 550 that includes the bond pads 562 along the first edge 552 thereof, and is fabricated to have a length more than that of a conventional fluid ejecting chip, such as the fluid ejecting chip 100 of FIG. 1, which have bond pads configured along respective breadths/shorter sides thereof, in order to route the power/control signals distribution through the bond pads 562 that are configured along the first edge 552, i.e., longitudinal edge, of the fluid ejecting chip 550. It is to be understood that other fluid ejecting chips, such as the fluid ejecting chips 510, 530 and 570, of the inkjet printhead 500 also have been fabricated to have a length more than the conventional fluid ejecting chips that have bond pads configured along respective breadths/shorter sides thereof.
Alternatively, manufacturing of an inkjet printhead may involve fabrication of fluid ejecting chips, such as a fluid ejecting chip 600 of FIG. 7 that is wider than a conventional fluid ejecting chip, such as the fluid ejecting chip 100 of FIG. 1 and the fluid ejecting chips of FIG. 5. Such a wide fluid ejecting chip may also assist in routing power or control signals distribution appropriately within the fluid ejecting chip 600 that includes a plurality of bond pads 602 and a plurality of wires 604. As depicted in FIG. 7, the bond pads 602 are configured along a first edge 606, i.e., longitudinal edge, of the fluid ejecting chip 600.
With regard to cost incur, FIG. 8 depicts a graph 800 that illustrates a comparison of print swath die cost for fluid ejecting chips (yielding 1 inch (″) print swath) with varying length and fluid ejecting chips (yielding 1″ print swath) with varying width for inkjet printheads. Specifically, the graph 800 depicts a curve 802 that is a fluid ejecting chip cost curve for varying lengths when fluid ejecting chip's width is held constant. Further, the graph 800 depicts a curve 804 that is a fluid ejecting chip cost curve for varying widths when the fluid ejecting chip's length is held constant. It may be observed that increasing the length of a 1 inch″ print swath fluid ejecting chip is costlier than increasing the width thereof.
Also, it has been observed that a large number of fluid ejecting chips, such as the fluid ejecting chips 510, 530, 550, and 570; and 600, may be required to be employed in an array to obtain longer print swaths. As a result, fabrication of inkjet printheads employing multiplicity of such fluid ejecting chips may be associated with high cost incur.
Accordingly, there still persists a need for an efficient and cost-effective inkjet printhead that includes fluid ejecting chips, fluid vias and bond pads, arranged in a manner that facilitates in obtaining a long print swath while eliminating skew effects on print quality and encapsulant footprint tolerances, and in optimizing power/control signals distribution within the fluid ejecting chips.